Lubricant compositions are used as coatings to reduce friction between the surfaces of moving parts and have a vast number of applications in almost every field of engineering practice. Lubricant coatings for medical uses have special requirements. Not only must these coatings reduce friction but they must also be capable of sterilization and be biocompatible, e.g.,be nontoxic and nonirritating. Examples of conventional lubricant coatings which have been used in the medical arts for years are mineral oil, petroleum jelly, and K-Y Jelly.TM. (Trademark of Johnson & Johnson Co.). These lubricants while effective have not proved entirely satisfactory for every application.
For example, nasogastric and nasojejunal tubes widely used for hyperalimentation must be lubricated on their exterior surfaces to facilitate their insertion through a nasal passage, throat, or the like and to avoid damage to soft respiratory or gastrointestinal tissue. Frequently, these tubes must also have lubricated interior surfaces to facilitate movement of stylets used within the lumen of such tubes to provide sufficient rigidity to properly position a tube within a patient's body.
The term "intubation devices" is used generically herein to refer to various tubes or other devices that are lubricated for insertion into any part of a human or other animal body including blood vessels, urinary and digestive tract passages, ears and the like. Examples of intubation devices are the nasogastric and nasojejunal tubes and stylets which are more fully described in U.S. Pat. No. 4,388,076, the text of which is incorporated herein by reference.
Uniformly coating intubation devices with conventional lubricants by a physician or other person during an intubation procedure is a messy, time consuming and inefficient procedure. Obviously, manually coating the interior surfaces (lumen) of tubes and like articles is extremely difficult. Similiar difficulties are experienced with intubation devices pre-coated with conventional lubricants. Such pre-coating also increases packaging and sterilization problems experienced in the manufacture and supply of such devices.
One approach to solving the foregoing difficulties and problems has been to provide the intubation devices with hydrophilic polymer coatings. These coatings provide a thin uniform coating that is dry and non-slippery until hydrated with water. While these polymer coatings have proved effective in some situations their major drawback has been that they take too long, sometimes longer than 30 minutes, to absorb enough water to achieve sufficient lubricity for insertion into a patient. Such delays are unacceptable in many medical situations often resulting in, for example, wasted time and in some emergency cases a threat to the health of the patient.
Various attempts have been made to modify these hydrophilic polymer coatings to accelerate their ability to take up water and reach sufficient lubricity for use. However, these attempts have generally not met with complete success. For example, one attempt involved treating a hydrophilic polymer coated intubation device with sulfuric acid. This can result in serious manufacturing difficulties and toxicity problems associated with the chemical properties and high viscosity of sulfuric acid.
Certain polymer coatings based on po1yvinylpyrrolidone (PVP) appear to hydrate rapidly enough but are plagued with a sliming problem. "Sliming" means that the coating becomes too soft and can be rubbed off an intubation device during ordinary use.
Accordingly, it is an object of this invention to provide a lubricant composition for coating applications which rapidly hydrates upon contact with water.
It is another object to provide a lubricant coating which has sufficient mechanical strength in a hydrated condition to resist sliming, abrasion, and the like typically experienced by intubation devices.